Electric apparatus



H. 0. STEPHENS.

ELECTRIC APPARATUS.

APPLICATION FILED DEC. 18.1916.

Figl. /0 Inventor:

|-lovvard O. Stephens,

/M/ 4 M His Attorney.

H. O. STEPHENS.

ELECTRIC APPARATUS.

APPLICATION FILED DEC. 18. I916.

1 ,345,7 1 2 ted uly 6, 1920.

2 SHEETS-SHEET 2.

Fig.2.

Inventor Howard Ostephens,

H is Attorneg UNITED STATES PATENT OFFICE.

HOWARD O. STEPHENS, OF PITTSFIELD, MASSACHUSETTS, ASSIG-NOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC APPARATUS.

Specification of Letters Patent.

Patented July 6,1920.

Application filed December 18, 1916. Serial No. 137,548.

ings. According to my invention windings I are so arranged thatone.terminal of a wind ing involving my invention is located atsubstantially the center of that winding, the opposite ends of thatwinding in effect being connected together and together providing theopposite terminal of the winding. From another aspect my inventioncontemplates a winding in which the turns are so arranged and connectedas to conduct current in the same directions about the flux path fromthe two ends of the winding to substantially the center thereof; fromstill another aspect my invention may be regarded as contemplating twomutually inductively related windings, as windings about a single fluxpath, in which the current simultaneously enters both windings at thetwo ends of the windings adjacent to each other and traverses bothwindings in the same directions about the flux path. My invention hasnumerous advantages some of which are enumerated toward the end of thedescriptive portion of this specification. My invention is applicableboth to high current and high voltage apparatus and windings, andespecially those in which a plurality of conductors are used in paralleland those having a ground connection.

My invention will be thoroughly understood and its particular andpeculiar application to transformers will appear from the followingdetailed description of o er tain transformer constructions embodyingit. Figure 1 illustrates quite simply, partially in section andpartially 1n elevat on, a transformer embodying my invention. Figs. 2and 3 are sections of parts of other transformer constructions embodyingmy 1nvention.

Fig. 4 diagrammatically illus-v trates a further application of myinvention to transformers. V

The transformer of Fig-.l-is particularly designed for high voltageWork; one end is grounded and it maybe used as one of three transformersY-connected on voltage side with the neutral grounded. The core 10 ofthis transformer is of the well known three-legged type, the primary andsecondary windings being placed about the middle leg 13. The low voltagewinding 11 is generally cylindrical in formand lies nearer the core leg13. Outside of 'the'low voltage winding l-lis placedthe'high voltagewinding which is constructed in accordance with my invention. This highvoltage fairly thin flat coils,of one turn of the con- 'ductorper layer,placed concentric with the low voltage winding 11 and distributed alongtheir common winding axis. The coil the high winding comprises a numberofdisks or 16 is a terminal coil of the high voltage winding, its outerturn being connected to the terminal '17 of the winding. The two coils18 and 19 at the opposite'sides' of and.

each other, and the interior terminals 20 of these coils are connectedtogether and 'together connected to the interior terminal 21 of theterminal coil 16. The coils 18, 22, 23', 24 and 25 comprise the portionof the high voltage winding between the coil 16 and one end of thewinding space; likewise the coil 19, coils like 22, 23, and 24, togetherwith the coil 27, comprise the portion of high voltage winding betweenthe coil 16 and the opposite end of the winding space. The'interiorterminals of the terminal coils 25 and 27 are grounded by beingconnected to the core at 26 and 28 respectively. The coils of each ofthe two groups at opposite sides of terminal coil 16 are connectedtogether in series between the terminal coil 16 and the groundedterminal 26 or 28, as appears from the drawing. The coils are so wound,arranged" and adjacent the terminal coil 16 are similar to connectedthat the turns progress about the posite end at 28. In this windingthen, the coils are so wound, arranged and connected as to conductcurrent in the same direction about the flux path (here the middle leg13 of the core) from the terminal 17 to the two ends of the windings at26 and 28. The magnetic flux resulting from the current in the uppergroup" of coils is thereforein the same direction as the magnetic fluxresulting from the current in the lower grouppf phase-system,Y-connected on the high volt- ,naL. The terminals 26 and 28 are,inefl'ect,

age. side. The terminal 17 is the line termi--' connected together, andtogether provide;

theflopposi-te terminahof the-high ,vOltageu winding. which for.Y-connectedtlflIlSfOIIIlr-r V ers would be connected .to similarterminals; of the other-transformers. to provideuthe middleaor neutralpoint of the Y. Ina-din dition :to terminals jQG ZLDCl 28 theuvindin'g'stackzmay be provided with taps, as shown at 37 and i 58, and explainedhereinafter;- r

nected to the lineyis extra heavily insulated between, turns rand 7 actsas,.-- the i. so-oalled bu-tier coil-t of the; highwoltage windinggq-The threeicoils' immediately atreach; side, ot i this coil; 16 ;are.also unusually heavilyi insiblatedbetween turns; but the insulationbetween the turnso-fthese latter coils is of, somewhat less strength-.than the insulation between the turns-of the-coil 16 in accordancewith usu'al-gpractice The remaining.

coils of the high-voltage winding are insu'-' lated :alikeandsubstantialfor normal volt-.

agein accordance with the usual practice.

This transformer-rillustrates the peculiar adaptability of windings ofmy invention to the socalled taperedv insula tion= thereof. 1 The-coils16-, 1S and 19 areiof the smallest external diameters and'thetgreatestinternal diametersof. any of the coils. of this wind .i1 g; the-coilsi22and 23- (and thelike coils at the opposite side of the'windingy are; ofgreater external and smaller internal diam-- eters, and the. coils 24:and 25 (and the coils like them at the opposite side of thewinding-including the coil 27 are of still greater external; diameters.and; smaller in r tern-a1 diametersi- The coils are all centered aboutthe core leg l3; The A respective coils are -therefore-spaced .from boththe leg 13- ;and theexternal legs ofthe-core, distances which aresomething Jikei proportional-to 1 the differences of potential betweenthe respective coils and the core. An insulating cylinder '30;-surrounds:the exterior of thelow,-voltage -winding lljor the whole length 1thereof.; It A similar insulating cylinder .31 (or at least twoinsulating plates) similarly insulate the high voltage windingfromtheouter -legs :-Iof the/core; by extending-along Y the inner surfaces iofthese .-=legs substan- 7 BEST AVAILABLE COP "d'er 30,111: disposedwithin and without the eleven middle coilsof the high voltage windingand still shorter insulating cylinders 33 Within and withoutrzthewinding vspan the three middle coils. These insulating; cylinders-andthe; spacing of the coils substantially complete the 1 insulationtbetween the high ivoltagewinding on, the one hand and ithe low voltagewinding. and the.

core onthe otller hand.- lVhere-the poten-.-

tial difference between the high voltagewinding; and ground-(core andlow voltage winding) is to be. expected to be- --;of 1 .the

greatest Value; that is jadj ajcent coils; 16, :18, 1

and "19, there-the; insulation- =isthe greatest,-

insulation-is-i of; an. intermediate; value and lat-lion; is.likewiseziof ithe lowe -s- I will be-obsenved that this zdifierence ininsulation strength; t a'pe ring,?". is secured @very: simply with thistypeg'ofwii'lding, avi-tl'r-a smallyamount V of; material, minimum num-.

'ber, of pieces,-pieces'-zo-f[simples-shape, and :m1n1m1un; lostwindingspace,--,and substan-- where this difi'erence nlS of anintermediate value; :as adjaeentcoils' .22 and '23., there the Theterminal, coil -l6 ,being directly c'on p -l-ineiterone .suchpair. Thesetaps are connected re-,

coils 25 and- 27 -a'nd1a't equal: distances i'rom the ends of thewindings zit-26 and 28 that is the number of; turnsbetween the tap 37and the end :26 is substantially. equal .-to the S provided WitlIfitapsiWhich do not disturb or shift the magneticxcenter of the winding intheir use F urthermore: the-tapsmay be -many times {aszinithe present-instance') located adj a'cent low voltage. partsof the winding, and;hence readily insulated. we

The transformer of Fig. 2 embodies my invention in asomewhatmodified-form; this spectively -to-.the external iterminals ofthe v number of turns-between thetap 538 and Y the end 28.1" To decreasethe number of active turns in the high} voltagev windings, theconnections .of the winding --to the coil transformer is of theinterleaved'disk coil type. The high voltage winding again isconstructed in accordance with my invention and comprises two lineterminal coils 40, the coils 42 at one side thereof and the coils 43 atthe opposite side thereof. The line terminals of the coils 40 areconnected together and together connected to one terminal 41 of thetransformer. One of the coils 40 and the coils 42 areconnected inseries, and likewise the other coil 40 and the coils 43 are connected inseries; the otherwise unconnected ends of. the coils 42 and 43 areconnected to the core. All these turns and coils are so disposedarranged and connected that current flows from the terminal 41 andthrough the terminal coils 40 and the coils 42 and 43 toward the twogrounded ends 44, in a single direction about the winding axis as in thepreceding case. The low voltage winding comprises the coils 46 and 47 interleaved respectively between certain of the coils 42 and certain ofthe coils 43. The

low voltage coils are shown connected in accordance with my invention inthis in-.

stance. The primary winding 50 and the secondary winding 51 (the lowvoltage winding) are substantially in the form of cylinders and areconcentrically disposed about the middle leg 52 of the transformer core.The winding 56 is of the usual form, the terminals being at the ends ofthe winding. The turns of the winding 51 however progress in the samedirection about the winding axis from the terminal 54 to the two ends ofthe winding at 55 and 56 as in the former cases; as before thetwoends 55and 56 of the winding together constitute the terminal of the windingopposite the terminal 54. The manner in which the turns are arrangedabout thewinding axis in this case appears more clearly in Fig. 4,winding 60. This transformer illustrates the application of my inventionto high current windings where a number of balanced parallel connectedconductors are desired,-

Fig. 4 illustrates another modification in that the winding 60 embodyingmy invention is disposed on two legs of the core. The terminals of thiswinding are at 61 and 62. From the terminal 61 'the winding progressesin the same direction about the adjacent core leg toward the two ends ofthe adjacent portion of the winding; the turns ofthe winding on theopposite core leg progress in a like manner from the .terminal 62 to thetwo ends of that portion of the winding. The turns of the portions ofthe winding on the opposite legs, are so related as to tend to produceflux in the same direction about the core when current enters at oneterminal (61 or 62) and simultaneously leaves at the other; theseportions of the winding are connected together at 68 and 69, the endsthereof adjacent the yokes. The low voltage winding of the transformerof this figure is arranged and disposed in a usual manner. The winding60 is provided with taps at 64, 65, 66, and 67. These taps are locatedat equal distances from the adjacent middle terminals (and likewise atequal distances from the connections 68 and 69). To reduce the number ofactive turns in this winding, the connections of the two windings arebroken adjacent 68 and 69 and the tap 64 is connected to tap 65 and thetap 66 is connected to tap 67. i g

It will appear from what has gone before that my invention possesses orresults in numerous advantages over the prior practice; among theseadvantages may be enumerated the following, some of which have beenindicated before :-It provides a system of parallel connected conductorswhich are readily balanced, that is, made to divide the total currentsubstantially equally among themselves which. is a particularlydesirable distribution for the charging current component since thecentral connec tion ofl'sets in large measure the effects of the endyokes on the shunted capacity to ground for the windings and permits acloser approach to the ideal logarithmic distribution of the initialelectrostatic charge. The winding is readily insulated, and generallyrequires a minimum amount of material and space. The ends of thewindings adjacent the end iron of the core are of low potential (in manycases) and it is therefore (in such cases) necessary to insulate thecoils from the end iron'only for this low voltage; from this thereresults saving in the amount of insulating material required and aconsiderable saving; in the amount of iron since thelength of the windowis materially decreased. The line or highest potential is (in manycases) at the center of the winding and a continuous barrier mayinsulate this point of the winding from the low voltage and the iron,eliminating the necessity of expensive and elaborate collars, orotherwise unnecessary extensions of the insulation, between the twowindings (or between the winding of my inven tion and the ground) toprevent arcing along the insulation to the low voltage winding orground. With the usual transformer construction in which one end of thehigh voltage winding is directly connected magnetic center of the highvoltage winding is shifted below (or above) the magnetic center of theadjacent low voltage winding, thus tending to increase the magneticforces in the transformer under the short circuit conditions; upon theother' hand, a transformer embodying my invention may have its end coil(or coils) extra heavily insulated and may be provided with taperedinsulation throughout while the magnetic centers of high voltage windingand low voltage winding are maintained opposite each other. The windingsof my invention may be more readily and strongly supported since it isunnecessary to provide the supports with high insulation strength; heavymetal coil supports may be used insulated only for the adjacent coilvoltage.

Hereinbefore and in the following claims I have had occasion to use theterms primary winding and secondary winding;" these terms are usedmerely for the sake of clearness and in order to readily differentiatebetween the two windings of a transformer. It will be understood that inpractice eitherwinding may be the primary winding and the other thesecondary winding.

While I have described the principle of my invention and the best mode Ihave contemplated to applying this principle other modifications willoccur to those skilled in this art and I aim in the appended claims tocover all modifications which do not involve a departure from the spiritand scope of my invention.

lVhat I claim as new and desire to secure by Letters Patent of theUnitedStates, is:

l. A stack of electrical windings having a single rectilinear windingaxis and provided with a terminal near the center thereof, the two endsof the windings being connected together and together providing theopposite terminal of said windings, the turns of said windings beingconnected and arranged to conduct current in a single direction aboutsaid winding axis in two paths from the center terminal of the windingto the opposite terminal thereof.

2. A stack of electrical windings comprising a plurality of disk coils,having a terminal connection adjacent the center of the stack andassembled to have a single rectilinearwinding axis about which the turnsof said coils are arranged to conduct current in a singledirection inparallel paths one at each side of said terminal connection, the ends ofsaid stack being connected together and to the other terminal.

3. A stack of electrical windings comprising a plurality of disk coilshaving a single rectilinear winding axis, one terminal of a disk coiladjacent the center of the windings being a terminal of the windings andthe other terminal of that coil being connected to the two coilsadjacent that coil, the coils at the two sides of said terminal coilbeing respectively connected in series and connected and arranged toconduct current in the same direction about the winding axis from saidterminal coil to the two ends of the windings.

4. A stack of electrical windings comprising a plurality of disk coilshaving a single rectilinear winding axis, one terminal of a disk coiladjacent the center of the windings being a terminal of the windings andthe other terminal of that coil being connected to the two coils adjacent that coil, said terminal coil being extra heavily insulated, thecoils at the two sides of said terminal coil being respectivelyconnected in series and arranged to conduct current in the samedirection about the winding axis from said terminal coil to the two endsof the windings.

5. A stack of electrical windings comprising a plurality of disk coilshaving a single rectilinear winding axis, one terminal of a disk coiladjacent the center of the windings being a terminal of the windings andthe other terminal of that terminal coil being connected to the twocoils adjacent that coil, said terminal coil being extra heavilyinsulated, the coils at the two sides of said terminal coil beingconnected and arranged to conduct current in parallel paths in the samedirection about the axis of the winding from said terminal coil to thetwo ends of the windings, and being provided with two taps adjacent theends of the windings, one at each side of the terminal coil and equallyspaced therefrom.

(3. A stack of electrical windings comprising a plurality of disk coilshaving a single rectilinear winding axis, one terminal of a disk coiladjacent the center of the windings being a terminal of the windings andthe other terminal of that terminal coil being connected to the twocoils adjacent that coil, said terminal coil being extra heavilyinsulated, the coils at the two sides of said terminal coil beingconnected and arranged to conduct current in the same direction aboutthe axis of the windings from said terminal coil to the two ends of thewindings, and the two ends of the windings being grounded.

'7. A stack of electrical windings provided with a terminal near thecenter thereof, the two ends of the windings being connected to ground,the turns of said winding being connected and arranged to conductcurrent in the same direction about the flux path from said terminal ofthe windings to the two connections to ground, and said windings beingfurther provided with a tap adjacent each grounded end, the two tapsbeing equally spaced from the grounded ends of the wlndlngs.

8. A stack of electrical windings provided with a terminal near thecenter thereof, the two ends of the windings being connected to theground, the turns of said windings be ing connected and arranged toconduct current in the same direction about the flux path from saidterminal of the windings to the two connections to ground, and theinsulation decreasing in value from the center terminal toward the endsof the windings.

9. A stack of electrical windings having a single rectilinear windingaxis and provided with a terminal near the center thereof, the two endsof the windings being connected to ground, the turns of said windingsbeing connected and arranged to conduct current in parallel paths in asingle direction about said winding axis; there being one path on eachside of the stack leading from the terminal connection at the center ofsaid windings.

10. A transformer comprising a core, and primary and secondary windingsabout a leg of the core, said primary winding comprising a plurality ofdisk coils, one terminal of a coil adjacent the center of the windingbeing a terminal of the primary winding and the other terminal of thatcoil being connected to the two coils adjacent that terminal coil, saidterminal coil being extra heavily insulated, the coils at the two sidesof said terminal coil being connected and arranged to conduct current inthe same direction about said core leg from said termi nal to the twoends of the winding and the two ends of that winding being grounded. 11.A transformer comprising a core, and

primary and secondary windings about a leg of the core, said primarywinding comprising a plurality of disk coils, one terminal-of a coiladjacent the center of the winding being a terminal of the primarywinding and the other terminal of that coil being connected to the twocoils adjacent that terminal coil, said terminal coil being extraheavily insulated, the coils at the two sides of said terminal coilbeing connected and arranged to conduct current in the same directionabout said core leg from said terminal to the two ends of, the winding,the two ends of that winding being grounded, and the winding beingprovided with two taps adjacent the grounded ends thereof, one at eachside of the terminal coil and equally spaced therefrom.

12. A transformer comprising a core, primary and secondary windingsabout a leg of I the core, the primary winding being provided with aterminal near the center thereof and the turns of said winding beingconnected and arranged to conduct current in the same direction aboutsaid leg of the core

